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  • 1
    Electronic Resource
    Electronic Resource
    Structure of porous cellulose acetate membranes and a method for improving their performance in reverse osmosis (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 13 (1969), S. 637-657 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Experimental data support the hypothesis that the surface layer of the asymmetric Loeb-Sourirajan type porous cellulose acetate membranes has a heterogeneous microporous structure. A general method is proposed for improving the performance of the above membranes in reverse osmosis, by which product rates are increased without decreasing solute separation. The method consists in pumping pure water past the back side of the membrane under just enough pressure for a sufficiently prolonged period of time; after such pretreatment, the membrane is used in the reverse osmosis experiments in the normal manner with the surface layer facing the feed solution. Back-pressure treatment at 400 psig for 85 hr on preshrunk and normally pressure-treated membranes increases the product rate by over 20% without decreasing solute separation in reverse osmosis experiments at 600 psig with the use of 0.5 wt-% NaCl-H2O feed solutions; with a different sequence of back-pressure treatment, similar results have been obtained in reverse osmosis experiments at 1500 psig also. The compaction effect of a normal membrane and that of a back pressure treated membrane are the same during continuous reverse osmosis operation under 600 psig; the effects of back-pressure treatment on a normal membrane and a compacted membrane are also the same. The pure water permeability data obtained in cyclic experiments show that the smaller pores on the surface layer are opened more than the bigger ones during the back side operation. The probable structural changes taking place in the film during back-pressure treatment are discussed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1969.070130407
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of medium and matrix composition on diffusivities in charged membranes (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1382-1384 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260270916
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  • 3
    Electronic Resource
    Electronic Resource
    Specific resistances of hydrophilic membranes containing ionogenic groups (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 19 (1975), S. 3029-3044 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper deals with an investigation of the dependence of specific resistances on pH for hydrophilic membranes containing ionogenic groups. Membranes based on poly(2-hydroxyethyl methacrylate) crosslinked with ethylene dimethacrylate were investigated. This basic structure was modified by copolymerization with ionogenic comonomers, i.e., methacrylic acid and/or diethylaminoethyl methacrylate. It is shown that the dependence of the specific resistance on pH passes through a maximum for cation-active membranes at pH ∼ 3.5, for anion-active membranes at pH ∼ 10, and for ampholytic membranes at pH ∼ 6. The effect of the content of ionogenic groups, network density, and the degree of neutralization of membranes on the above dependence is discussed. In the final part of the paper the results are compared with more hydrophilic systems based on poly(2-hydroxyethyl acrylate) and it is shown that maxima in the dependence of specific resistances on pH can be suppressed by increasing the hydrophilicity of polymers.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1975.070191108
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  • 4
    Electronic Resource
    Electronic Resource
    Permeability of heterogeneous membranes based on methacrylic acid (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 2245-2251 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The permeability of H+, Na+, insulin, and hemoglobin through porous membranes made of crosslinked poly(methacrylic acid) was investigated at different pH values on both sides of the membrane. It was shown that a change in the charge of the protein during its transport through the membrane might raise the driving force of the process so much that the permeability coefficient of the protein through the membrane would be higher than in solution. In the case reported here, the flow of the protein may be regarded as partial electrophoresis in a porous medium.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070230803
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  • 5
    Electronic Resource
    Electronic Resource
    Biological tolerance of poly(N-substituted acrylamides) (1973)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 7 (1973), S. 111-121 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The biological tolerance of poly(N-substituted acrylamides) implanted subcutaneously to rats and pigs was investigated. Besides a macro- and microscopical evaluation of the implant and its surroundings, the surface changes of the implants were determined by means of a Stereoscan electron-optical microscope;the results obtained confirmed the very good in vivo stability of the polymers used.The histological analysis showed that all the polymers under investigation are very well tolerated by the organism and do not provoke any unfavorable reaction. The implants become surrounded with a granulation tissue which is gradually replaced by fibrocytes and collagen fibers situated in the basic substance staining positively with the alcian blue and PAS. In contrast with some authors we did not find a thicker capsule surrounding the implant on the sharp edges but on the flat planes. No calcification could be observed within the intervals investigated. The surface changes, which were studied electronoptically, were insignificant and connected with the way in which the implant was treated. No indications of malignant growth were observed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820070109
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  • 6
    Electronic Resource
    Electronic Resource
    Biocompatibility of poly(2,4-pentadiene-1-ol) (1974)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 155-161 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In our earlier papers1-4 we reported on the biocompatibility of esters and substituted amides of methacrylic and acrylic acids which are suitable for the development of specific biological functions.5 The results described in these papers1-4 enabled some relationships to be formulated which exist between the chemical and physical structure of the implants, on the one hand, and the process of their healing-in and calcification, on the other.6.A number of biological applications require materials having rubber-like mechanical properties. With this aim we started in our laboratory the development of hydrophilic elastomers based on dienes containing hydrophilic groups. Poly(2,4-pentadiene-1-ol)7 was the first polymer of this type obtained which had mechanical properties suited for biomedical applications. Its biocompatibility with living tissue is reported in this paper.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820080205
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of molecular weight (Mw) of N-(2-hydroxypropyl)methacrylamide copolymers on body distribution and rate of excretion after subcutaneous, intraperitoneal, and intravenous administration to rats (1987)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 21 (1987), S. 1341-1358 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A copolymer of N-(2-hydroxypropyl) methacrylamide (HPMA) and N-methacryloyltyrosinamide was prepared and fractionated using Sepharose 4B/6B (1:1) chromatography to produce eight HPMA copolymer fractions of narrow polydispersity and mean molecular weight (Mw) ranging from 12 to 778 kD. These fractions were radioiodinated and injected intravenously, subcutaneously, and intraperitoneally into rats. Their bloodstream-concentration profiles were monitored and rates of excretion assessed. Following intravenous administration the circulating blood volume available to the copolymers was not molecular-weight-dependent. A molecular-weight threshold limiting glomerular filtration was identified at approximately 45 kD, and preparations greater than this threshold were lost from the bloodstream only slowly by extravasation. Molecular weight did not influence the movement of copolymers from the peritoneal compartment to the bloodstream after intraperitoneal injection. The transfer rates observed could be accounted for by bulk phase lymphatic drainage alone, no transcapillary routes being implicated. Following subcutaneous administration the largest HPMA copolymer fraction (Mw = 778 kD, diameter approximately 30 nm) showed increased retention at the site of injection, approximately 20% of the dose remaining there after 21 days. This could result from physical restriction of movement or from internalization into local phagocytic cells. The smaller copolymer fractions moved readily into the bloodstream whence they were either lost in the urine or they gradually penetrated into other tissues and organs. Long-term (21 days) body distribution of copolymers following both intraperitoneal and subcutaneous administration showed size-dependent accumulation in organs of the reticuloendothelial system.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820211106
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  • 8
    Electronic Resource
    Electronic Resource
    New types of synthetic infusion solutions. III. Elimination and retention of poly-[N-(2-hydroxypropyl)methacrylamide] in a test organismFor Part II of this series, see Štěrba et al.3 (1976)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 10 (1976), S. 953-963 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The elimination and retention of a new, fully synthetic plasma prosthesis of Czechoslovak origin under the working name of Duxon (poly[N-(2-hydroxypropyl)methacrylamide]) was investigated in experiments on rabbits by using a 14C-labeled polymer. Results published earlier on elimination have been confirmed and extended. Retention was examined after repeated application. The effect of molecular weight prevailed both in elimination and in retention. Polymers of lower molecular weights, which possess a good therapeutical effect, are not permanently deposited in the organism.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820100612
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of porosity of heterogeneous poly(glycol monomethacrylate) gels on the healing-in of test implants (1971)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 5 (1971), S. 447-458 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Test implantations were carried out on rats in order to investigate the effects of porosity of heterogeneous poly(glycol monomethacrylate) gels on their healingin. The porosity was varied by changing the water content in initial monomeric mixture. The histological analysis has shown that spongy polymers containing 50 and 60% of water in the initial mixture are healed-in similarly to the homogeneous gel by encapsulation with collagen fibrous tissue. In polymers having higher content of water in the initial mixture, i.e. higher porosity, the vessels from the new formed fibrous capsula penetrate into the implant. The higher the porosity, the narrower the capsula and the broader the zone of cellulization and new-formed capillaries, penetrating into the implant. In the case of polymers of higher porosity, giant multinuclear cells are observed in the margin of the implant. The positive Kóssa's calcium reaction was found only sporadically on the margin of the implant.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820050503
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  • 10
    Electronic Resource
    Electronic Resource
    Biological tolerance of poly(N-substituted methacrylamides) (1971)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 5 (1971), S. 197-205 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Experiments were investigated on animals' biological tolerance of the copolymers of N-substituted methacrylamides with the monomers which can be considered for uses in the modification of the monomeric backbone. The group of N-substituted methacrylamides is the second one in the series of hydrophilic polymers arranged according to their increasing resistance to hydrolysis, and it follows immediately after the esters of methacrylic acid. Histological analysis has shown that the copolymer of N-ethyl methacrylamide with methyl methacrylate is the best tolerated polymer of this group. In the case of copolymers with butyl acrylate and butyl methacrylate, in the first days after implantation a stronger and more cellular capsula was formed, and an inflammation was observed in the surroundings of the encapsulated implant. Starting from day 30, however, no differences are found in the encapsulation, and the result of healingin of all the polymers is always favorable. No cancerogenic effects were observed; calcification was found only sporadically in the case of the copolymer with butyl methacrylate.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820050307
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